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Weed Science Society Ranks Most Troublesome Weeds

Weed Science Society Ranks Most Troublesome Weeds

5/24/2017 8:34:00 PM/Categories: General News, Today's Top 5, National News

WESTMINSTER, Colorado – MAY 23, 2017 – A recent survey conducted by the Weed Science Society of America (WSSA) ranks Palmer amaranth as the most troublesome and difficult to control weed in 12 categories of broadleaf crops, fruits and vegetables, while common lambsquarters ranks as the weed most commonly found.

Almost 200 weed scientists across the U.S. and Canada participated in the 2016 survey, the second conducted by WSSA.  A 2015 baseline survey explored the most common and troublesome weeds in 26 different crops and noncrop areas.

The current survey ranks the following weeds as the most troublesome or the most common among broadleaf crops, fruits and vegetables:



Most TroublesomeMost Common
1Palmer amaranth1common lambsquarters
2common lambsquarters2foxtail (giant, green, yellow)
3horseweed (marestail)3morningglory (ivyleaf, pitted, tall)
4morningglory (ivyleaf, pitted, tall)4Palmer amaranth
5waterhemp (tall, common)5redroot pigweed
6nutsedge (yellow, purple)6waterhemp (tall, common)
7kochia7horseweed (marestail)
8common ragweed8common ragweed
9giant ragweed9barnyardgrass
10nightshade (eastern black, hairy)10velvetleaf

Six weed species appeared on both the “most troublesome” and “most common” lists, including Palmer amaranth, common lambsquarters, horseweed, morningglory, waterhemp and common ragweed.  “Weed scientists have confirmed multiple cases of herbicide resistance in all six of these weed species, except for the morningglories where there is suspected resistance to glyphosate,” says Lee Van Wychen, Ph.D., science policy director for WSSA. “While each of these species has evolved traits that make them widespread and tough competitors in broadleaf crops like soybeans and cotton, there is no question that their difficulty to control with herbicides has pushed them to the top of the list in this survey.”

WSSA also sorted the survey data to produce the following crop-specific results:



alfalfaCanada thistledandelion
canolakochiawild oat
cottonPalmer amaranthmorningglory (ivyleaf, pitted, tall)
fruits & nutsfield bindweedhorseweed (marestail)
peanutsnutsedge (yellow, purple)Palmer amaranth
pulse cropscommon lambsquarterscommon lambsquarters
soybeanshorseweed, waterhemp (tall, common)waterhemp (tall, common)
sugar beetscommon lambsquarterscommon lambsquarters
vegetablesnutsedge (yellow, purple)common lambsquarters

Although listed as the most troublesome weed in cotton only, Palmer amaranth was ranked first in the overall survey based on the number of respondents who cited it as a problem. Common lambsquarters is widely distributed across the northern half of the United States and southern Canada.  It is not surprising that it ranked as the most common weed in sugar beets, vegetable crops and pulse crops, such as dry edible beans, lentils and chickpeas.

WSSA plans to conduct habitat-specific weed surveys annually. The 2017 survey will focus on weeds in grass crops, pasture and turf, while the 2018 survey will focus on weeds in aquatic environments, natural areas and other noncrop settings.

The 2016 survey data is posted online at For more information specific to herbicide-resistant weeds, see the International Survey of Herbicide Resistant Weeds, available at


Source: Weed Science Society of America 


1 comments on article "Weed Science Society Ranks Most Troublesome Weeds"


Juanita McCollough

5/25/2017 8:19 AM

Leafy Spurge did not make the list. We find that to be the most troublesome and impossible weed to eradicate on our ranch.

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